Sofa



FIG. 1 is a front elevational view of a sofa showing my design;

FIG. 2 is a front perspective view;

FIG. 3 is a side elevational view taken from the right in FIG. 1;

FIG. 4 is a front elevational view of a sofa showing a second embodiment of my design;

FIG. 5 is a front perspective view; and

FIG. 6 is an end elevational view taken from the right in FIG. 4. 

The ornamental design for a sofa, as shown and described. 